Oxidation chemistry using enzymes is approaching maturity and practical applicability in organic synthesis. Oxidoreductases (enzymes catalysing redox reactions) enable chemists to perform highly selective and efficient transformations ranging from simple alcohol oxidations to stereoselective halogenations of non‐activated C−H bonds. For many of these reactions, no “classical” chemical counterpart is known. Hence oxidoreductases open up shorter synthesis routes based on a more direct access to the target products. The generally very mild reaction conditions may also reduce the environmental impact of biocatalytic reactions compared to classical counterparts. In this Review, we critically summarise the most important recent developments in the field of biocatalytic oxidation chemistry and identify the most pressing bottlenecks as well as promising solutions.

Light has received increased attention for various chemical reactions but also in combination with biocatalytic reactions. Because currently only a few enzymatic reactions are known, which per se require light, most transformations involving light and a biocatalyst exploit light either for providing the cosubstrate or cofactor in an appropriate redox state for the biotransformation. In selected cases, a promiscuous activity of known enzymes in the presence of light could be induced. In other approaches, light-induced chemical reactions have been combined with a biocatalytic step, or light-induced biocatalytic reactions were combined with chemical reactions in a linear cascade. Finally, enzymes with a light switchable moiety have been investigated to turn off/on or tune the actual reaction. This Review gives an overview of the various approaches for using light in biocatalysis.

In the field of green chemistry, light – an attractive natural agent – has received particular attention for driving biocatalytic reactions. Moreover, the implementation of light to drive (chemo)enzymatic cascade reactions opens up a golden window of opportunities. However, there are limitations to many current examples, mostly associated with incompatibility between the enzyme and the photocatalyst. Additionally, the formation of reactive radicals upon illumination and the loss of catalytic activities in the presence of required additives are common observations. As outlined in this review, the main question is how to overcome current challenges to the exploitation of light to drive (chemo)enzymatic transformations. First, we highlight general concepts in photo‐biocatalysis, then give various examples of photo‐chemoenzymatic (PCE) cascades, further summarize current synthetic examples of PCE cascades and discuss strategies to address the limitations.

Enzyme gewinnen immer mehr Bedeutung als Katalysatoren für organische Oxidationsreaktionen. Mit Oxidoreduktasen stehen dem Chemiker vielseitige Werkzeuge für selektive und effiziente Oxidationsreaktionen zur Verfügung. Ihr Spektrum reicht von einfachen Alkoholoxidationen bis hin zur stereoselektiven Halogenierung nicht‐aktivierter C‐H‐Bindungen. Für viele biokatalytische Oxidationen ist bisher kein chemisches Pendant bekannt. Daher ermöglichen Oxidoreduktasen kürzere Syntheserouten. Darüber hinaus sind die generell milderen Reaktionsbedingungen biokatalytischer Oxidationen attraktiv. In diesem Aufsatz fassen wir einige aktuelle Entwicklungen im Bereich der biokatalytischen Oxidation zusammen. Wir beschreiben auch derzeitige Grenzen und vielversprechende Lösungsansätze.